Steam system control unit



July 18, 1950 o. A. HUNT ETAL STEAM SYSTEM CONTROL UNIT 2 Sheets-Sheet l Filed Feb. 28, 1949 5.23. aav-L mimi. II

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July 18, 1950 o. A. HUNT TAL 2,515,652

STEAM SYSTEM CONTROL UNIT Filed Feb. 28, 1949 2 Sheets-Sheet 2 wAsH wA TANK EQUIPMENT 27 HEAT 6, ExcHANER EQunPmEN 26' HEAT 6 ExcHANaER Patented July 18, 1950 2,515,652 STEAM SYSTEM CONTROL-UNIT Orville A. Hunt and Louin Tiller, Chicago, Ill., assignors, by mesne assignments, to Reconstruction Finance Corporation, Chicago, Ill., a co1'-Y poration of the United States Application February 28, 1949, Serial No. 80,802

17 Claims. 1

Our invention relates to steam systems with special reference to steam systems for drying operations and is directed to improvements on the type of steam system set forth in the Harrison et al. Patent 2,366,322, issued January 2, 1945.

Other copending applications disclosing the subject matter related hereto are: S. N. 78,842, filed February 28, 1949, S. N. 78,605, filed February 26, 1949; S. N. 78,843, led February 28, 1949; S. N. 78,604, led February 26, 1949; and S. N. 777,894, led October 4, 1947.

`Our invention refers to heating systems in which steam acting through heat-exchange devices processes some material such as cloth, paper, plastics, or the like, and in which steam also is used to heat some liquid extraneous to thesteam system; .that is to say, some liquid apart from the make-up water requirements of the steam system itself. The extraneous liquid may, for example, be the water that must be heated for washing clothes in a steam laundry or may be any other liquid in any other industry where a steam system is used'for processing.

The general object of our invention is to achieve greater efficiency and economy in a steam system such as described and, more specifically stated, is to do so by means involving the transfer of heat to the extraneous liquid.

The preferred practices of our invention employ a release valve at the end of the return line to draw a fraction of the steam all the Way through the system to create velocity inthe system as well as to sweep condensate out of the equipment back to the boiler room. For overall economy, this fraction of steam that is drawn from the return line may be used to preheat make-up water for the system.

Whenever the make-up water demand of a steam system appears to be especially low because the natural losses from the system are exceptionally low, the amount of steam that must be released to create optimum velocity may be more than can be consumed by the available relatively small quantity of make-up water.

The present invention contemplates meeting this situation by using the extraneous liquid to consume heat from the return end of the clear channel system in such a way as to set up whatever velocity is desirable without waste of released steam. The transfer of heat to the extraneous liquid may be direct or indirect, and the heat may be taken either from the return line above the release valve or from the releaseduid on the discharge side of the valve.

Two different practices of the invention are described by Way of example. In the rst practice of the invention, heat is taken fromthe return line above the release valve. The extraneous liquid is employed to condense steam either directly or indirectly, thereby creating velocity in the system and to that extent reducing the need for releasing velocity-promoting steam from the end of the system. Thus without sacrificing velocity, the amount of steam released may be reduced to the actual amount needed to `preheat and deaerate the make-up water for the boiler. In the second practice of the invention, heat is transferred from the released steam to the extraneous liquid, preferably by indirect methods. In this manner any steam released from the system is excess of the requirements for preheating make-up water may be completely consumed in raising the temperature of the extraneous liquid.

The various objects and advantages of the invention will be apparent from the following detailed description taken with accompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

Fig. 1 is a diagram of a typical laundry steam system incorporating one form of the new unit; and

Fig. 2 is a similar diagram illustrating another practice of the invention.

For the purpose of disclosure and to illustrate the principles involved, the present disclosure will be directed to a steam system fora laundry, but it will be clear to those skilled in the art that the invention is applicable to many different l-lelds. y

Fig. 1 illustrates how the invention may be embodied in a piece of apparatus that may be manufactured as a self-contained unit forinstallation in steam plants, usually in the boiler room. This form of the unit includes an upright tank or receiver l0 and a housing or casing associated therewith.

Fig. 1 shows six pipes connected to the master control unit. These six pipes are: an inflow pipe l2 for conducting to the unit the so-called extraneous liquid which the steam system heats in addition to carrying out its primary function of drying clothes; an outflow pipe I3 for carrying the' extraneous liquid away from the unit; an inflow pipe l5 for supplying Vnew water to theunit to be used for make-up for the boiler in thesteam system; an inow pipe l0 connected to the discharge side of the usual boiler feed pump; an outflow pipe l1 which is the boiler feed line forsupplying water to the boiler.; lan inilow pipe i8 which is the return line of the steam system; and at a lower level, an outow pipe that is connected to the intake side of the boiler feed pump. If desired, an additional vent pipe 2| may be connected to the vent opening of the tank I0.

Fig. 1 shows 'diagrammatically the principal elements of a steam system including the important parts of the new master control unit. The parts of the unit itself are shown inside a rectangle 22 indicated by a broken line. Everything inside this rectangle is inside the casing of the unit.

In the system shown in Fig. l, steam from a boiler 23 is supplied through a header 25 to a plurality of equipment heat exchangers or steamusing devices 26. Such devices may be, for example, the various machines in a laundry or the drying equipment used in paper manufacture, plastics, etc. Return pipes 21 from the various pieces of equipment connect with the previously mentioned return line I8.

Instead of traps, each of the return lines 21 is provided with fa suitable restriction such as a nipple 28 of a relatively small diameter. It will be noted that in such an arrangement there is open communication from the return line |8 back through the various pieces of equipment 26 to the boiler 23 so that lowering the pressure in the return line |8 will cause flow velocity responses in each of the steam-using devices. In other words, the various pieces oi equipment 'and the return line form a continuously clear channel Yfrom Vthe boiler for continuous flowpromoting pressure communication through the LAsystem and through the equipment.

The return line |8 lis terminally connected to the side of a steam separatorl 3| which preferably, but not necessarily, also serves as a heat `exchanger for using the returned condensate to heat new make-up water. The cornbined heat exchanger and separator 3| is shaped kand dimensioned to permit the vcondensate to separate from the steam and, if desired, suit'- able bafes 32 may be added to `'facilitate such separation.

The condensate that is separated from the steam gravitates through a pipe 33 to the intake side of a condensate pump 35 that is included in the vworking vparts of the master control unit. The 'pump 35 discharges the condensate upward through a pipe 36. Preferably,

the pump {i5-operates continuously.

A valve 31 is provided in the pipe 33 to cut the heat exchanger off from the pump if desired. When the valve 31 is closed, all of the 'condensate and steam that reaches the heat 4exchanger 3| must flow from the heat exchanger through a pipe 38. The pipe 38 .conducts fluid from the return line |8 into the receiver tank l0.

The pipe 38 leads to a two-stage combined heater and mixer 40 which in turn communicates with a spray head 4|. Flow through the pipe 38 into the tank I0 is controlled by a thermostatic valve 42 having a thermostat bulb 43 extending into the spray head 4|. The thermostat control is such that the valve 42 opens in response to decrease in temperature of the thermostatic bulb 43 and closes in response to increasing temperature of the bulb. The critical temperature at which the thermostatic valve 42 opens and closes may be varied by virtue of a manual adjustment 45, on the valve.

The steam or steam mixed vwith condensate that flows through the pipe 38 and the valve 42 enters a central upright passage 46 in the twostage heater 4D and divides, one portion owing into an upper jet 41 for the first-stage heating of new water, and the other portion flowing into a lower jet 48 for the second-stage heating. The upper jet 41 is directed into a Venturi throat 50 and the lower jet 48 is directed into a corresponding Venturi throat 5|, each jet and throat forming a low pressure space for the introduction of fluid.

New water for the steam system supplied by the previously mentioned pipe l5 passes through a oat-controlled valve 52 and enters the twostage heater 40 in the low pressure space between the rst jet 41 and the Venturi throat 55. The resulting mixture ows through a lateral connecting passage 56 into the low pressure space between the second jet 48 and second Venturi throat 5|, where it is joined by the second portion of hot uid from the pipe 38. From the two-stage heater the heated water flows into the spray head 4| in heat-exchange relation with the thermostatic bulb 43. The water is not only heated but is also under considerable pressure in the spray head 4| and is discharged downwardly through the spray ports with considerable violence.

Preferably the tank l0 is maintained slightly above atmospheric pressure, say, 3 or 4 pounds above atmospheric pressure. For this purpose, the tank is of closed construction and the vent 2| is provided with both a vent valve 58 and a relief valve 59. The vent valve 58 may be adjusted at a slightly open position to maintain the desired pressure in the tank of 3 or 4 pounds per square inch, and the relief valve 59 may be adjusted to pop off at, say, 8 to 10 pounds per square inch.

It is contemplated that the spray capacity of the spray head 4| will be so limited relative to the input of uid that the pressure in the spray head will rise above the pressure prevailing in the tank I0 when the thermostatic valve 42 is open. Under such conditions, the pressure in the spray head may go substantially above the tank pressure. It is further contemplated that the extent to Which pressure will rise in the spray head under given conditions may be varied either by varying the number of spray openings or by changing the size of the spray openings.

When the heated water is released in vfine droplets from the spray head 4| into the interior of the tank l0, the droplets are shattered by fiashing action and the non-condensible gases are effectively released from the Water to escape upwardly through the tank vent. A vent condenser in the upper part of the tank Vnot only reclaims heat from the escaping gases but also condenses any steam that may tend to escape with the gases, the recovered condensate dripping to the bottom of the tank.

The tank contains in its lower portion a reserve body 60 of deaerated make-up water supplied by the above-described spray action. When the level of this body drops, a suitable float 6| opens the previously mentioned valve 52 by suitable mechanical means including an upwardly extending operating rod 62. If the level of the water body 6D rises to@ high, it overows through an overflow pipe 63. To prevent the release of pressure through the overflow pipe 63, it is provided with a float valve 64 that is normally closed but opens automatically whenever the water level in the tank rises unduly. When desired, the

whole water content of the tank may beilushedv previously mentioned pipe 20 to the intake sidel of the usual boiler feed pump 61 and is discharged by thev pump into the previously mentioned pipe I6. The pipe I6 is connected to the inlet end of a heat-exchangecoil 68 in the previously mentioned combined heat exchanger and steam separator 3|. The outl-et end of this coil 68 is joined to the previously mentioned Apipe 36 leading to the boiler feed line I1.

The feed water pump 61 may be controlled in a well-known manner by means responsive `to changes in the water level in the boiler 23 or in some practices of the invention may be manually adjusted to run continuously at approximately the rate required to keep the boiler level constant. In either event, the float 6| in the master control tank I will drop to cause new water to be supplied to the system in accord with the boiler demand.

The previously mentioned outilow pipe I3 from the master control unit leads to the closed water tank |24 for supplying the wash water required in the laundry. This wash water is the so-called extraneous liquid heated by the steam system, meaning that it is not make-up Water required by the steam system itself. The make-up `water is supplied solely through the previously mentioned inflow pipe I5.

The pipe I3 may supply all of the wash water to the tank |24 or may supply any proportion of the total demand, and as will be explained, preferably the master control unit provides means whereby any desired proportion of the ilow through pipes I2 and I3 may, in eiTect, be bystriction 8| into a return pipe 82 leadingto the previously mentioned return line I8.

In a typical laundry as much as half of the total steam consumption is required for heating the wash water, but in the system here described, all of the condensate so formed is kept in a closed pipe system and returned in toto to the boiler room. It will be apparent to those skilled in the art that a steam system of `this character may have an exceptionally low demand for make-up water. On the other hand, if the releasel valve 42 is relied upon entirely to maintain the most eifective flow velocity in the system, it may be necessary to release a relatively large quantity of steam, much larger than can be utilized in preheating the make-up water inside the master control unit. This is the problem to which the present invention is directed.

In Fig. l this problem is solved by the following arrangement for utilizing the cooling effect of the extraneous liquid.

As heretofore mentioned, the wash water supply, or at least a portion of the total supply, enters the master control unit by pipe I2 andleaves by pipe I3.A Inside. theunitthe two pipes I2 and I3 are preferably' directly interconnected by a pipe having' two spaced manually operated 88 extends from the pipe 85 to the inlet of the previously mentioned vent condenser 80. Flow to the vent condenser may be controlled by a suitable valve 90. From the outlet of the vent condenser a pipe 9| controlled by a valve 92 connects with the pipe between the two valves 86 and 81. Branching from the pipe 9| is a pipe 93 controlled by a valve 95. This pipe 93 connectsfwith the inlet of a second heat-exchange coil 96 in the separator 30 and the outlet of the coil is connected by a pipe 91 with the previously mentioned pipe 85 downstream from the valve 81.

Operation 1 The manner in which the described system operates may readily be understood from the foregoing description. The adjustment 45 of the thermostatic valve 42 is set at a temperature high enough to release steam from the end of the system in sucient quanitity to keep the pressure in the return line I8 substantially below the pressure of the steam supplied to the pieces of laundry-drying equipment 26. As a result, there -is y continuous Aflow of steam into and through the pieces of equipment to the return line I8. The fraction of steam thatpasses beyond the Vequipment is thoroughly intermixed with the condensate in the restrictions 28, thereby entraining the condensate for conveyance through the return line I8 to the end of the system.

In a steam system having approximately 100 pounds per square inch gauge pressure in the spray header 25, the setting of the thermostatic valve may be, for example, somewhat above 230 F. In any event, the temperature setting will be above the normal temperature prevailing inside the tank I0. If the tank I0 has a pressure, say, l to 6 pounds gauge, the temperature in the tank willbe in the range of 224-230 F.

Since the temperature of the master control tank is below the temperature setting of the thermostatic valve, the tank tends to cool the thermostatic bulb 43 for opening action of the valve 4,2. Whenever the bulb 42 opens, however, the high-temperature iluid released from .K the separator 3| again heats the thermostat to cause closing action of the valve.

Since a temperature above 230 F. cannot be attained in the spray head 4| as long as the spray head. interior is at the same pressure as the interior of the tank I0, the initial flow of steam from the thermostatic valve or the initial flash of steam by flash action from vcondensate released through the valve does not have a temperature above 230 F. The restrictive laction of the spray openings, however, is eiective to cause rising back pressure in the spray header- The temperature in the spray header rises correspondingly and soon climbs above the temperature setting of the thermostatic valve. It is apparent then that the flow passage from the thermostatic valve 42 to the discharge openings of the spray header 4I functions as a pressure accumulation space to make possible a relatively high temperature required for valve control as well as forthe deaeration of make-up water.

Whenever new make-up water is required. vthe `oat 5I lowers to open the water valve 52, and the consequent yflow of water into the two-stage mixer JI III cools the thermostatic bulb 43 forl opening action ofthe valve.

In the usual .method of operation, the flow of new water is adequate to keep the thermostatic valve open in opposition to the heating effect of the uid from the return line so that the thermostatic valve staps open as long as .the flow .of new water continues.

The function of the vent condenser 80 is to condense steam inside the tank I0, thereby lowering fthe tank pressure and temperature. The resultant cooling action on the thermostatic bulb 43 causes opening action of the valve 42. Thus, the vent condenser inside the pressure tankr supplements the cooling action of new make-up water to increase the amount of fluid released from the return end of the system. At the same time, the condensing action of the vent condenser salvages the heat content of the released steam.

In thel preferred mode of operation, water from the inflow `pipe I2 ows through the vent condenser 80 and the heat-exchange coil 9B in series, the valves 85, 81, and 92 being closed and the valves 90 and 95 being open. The water flowing into the coil 95 has been preheated by the vent condenser 80 but is .nevertheless far below the temperatureof steam in the separator 3 I. As a result. the now of water through the coil 96 causes steam to condense in the separator and, of course, such condensation lowers the pressure at the end of the return line to promote steam now through the system.

It is apparent that the make-up water entering the master control unit to cool the thermostatic bulb 43 accounts for only part of the total velocity created in the system and consumes only a part of the steam that reaches the end of the system. The vent condenser 90 accounts for additional velocity by its cooling effect on the thermostatic bulb and condensation of steam inside the tank. Finally, the condensing action of the coil 96 accounts for the rest of the vtotal velocity and consumes the rest of the steam that reaches the end of the return line.

Upon analysis itis seen that B. t. u.s.are transvferred from the end of the return line of the steam system to the wash water for preheating ofthe wash water, and since a very large quantity of wash water is consumed in laundry operations, as many B. t. u.s may be transferred as may .beneeded tcreach whatever velocity level is found desirablein the steam system.

While in the describedpractice of the invention .both .the vent condenser 8G and the steam-condensing coil 9.6 are used, obviously either may be used alone. .To use the vent condenser Sila-lone, valves and 95 areclosed and valves 81,90, and .92 Iare open. To use the coil .95 in the separator 3| alone, valves '90 and 87| are closed and valves I86, 92, and.95 are open.

The thermostatc valve-42 `may completely close or only nearly close in response to rising temperature,.`and the valve may be either .a quick-'acting valveor a slow-acting valve. If a slow-.acting valve isusedit will tend to stay open at an equilibrium-position in the absence of make-up water now with the released steam condensed lby the vent condenser 89. Whenever new make-up water .is admitted through thepipe |.5,.the valve .will merely open Wider.

Only high-temperature water reaches .the boiler 23 because, in thefirst place, the condensate that isreturned directly to the'boiler .bythe pump 35 .isnot-.permitted to drop to atmospheric pressure, and, in the second place, yall new water added to the system is .effectively preheated. 'Infa system using steam at 100 pounds v,per square inch gauge,

the condensate. discharged by the pump 35 will be well'a'bove 300 F'. The new deaerated water, already preheated to above 212, is further heated under pressure in the coil 6a before intermixing with the .condensate in the pipe 36, so that the final mixture of condensate and make-up water usually reaches the boiler at above 300 F.

The second form of the invention The second for-moi the invention shown in Fig. 2 ris, in large part, similar to Fig. l, as indicated by the use Vof :corresponding numerals to indicate corresponding parts.

One difference is that a vent condenser `53 cooled by make-up water is used instead of the previously described vent condenser .8.0 rcooled by the :extraneous liquid. Cold .make-up water from the .inflow pipe i5 flows into the vent condenser 53 under control. of the lpreviously mentionedfloat valve l'52., and .from the vent ,condenser flows through a pipe 55 -to the ltwo-.stage heater 4|).

A second difference .is that the separator .31| at the end of vthereturn line has only one heat-exchange coil, a, coil 69 that serves the same function as the vpreviously lmentioned coil 63 and is connected iin substantially the same manner to thep'ipes v|15 and 3;E.f.

In :the second yform of the invention, B. t. u.s are rtransferred .from the end of the return line of :thesyslem y.to the wash water in the tank |24 bythe following arrangement. The wash water in :the :tank :|24 is heated by the steam Qcoil .|23 in the usual manner, but in this instance the returns from the steam coil drain .into a trap |22.

Theacondensate Ifromthe trap |22 passes through a .coil lglfl 'in a heat exchanger l-l-Q and then is :carriedfb-y fa pipe -|4 to .the `previously mentioned -pi-pe Eli-in the master-control unit. All or-a .part ,of-.the wash Iwater, supplied to the tank |24flows from a supply pipe |20 into the heat .exchanger ||l to cool the coil. Hand `then flows vthrough a pipe |2|,;into,the tank |24.

The heat exchanger M9 is shown aspositioned outside the cabinet or casing of the mastercon- .trolsunit represented bythe rectangle 22 but in some practices of Ythe invention may be inside the cabinet.

In thevsecond form `of the invention Ithe pre- .heatingof .the make-up water in the heat exchanger |I9fcool'sthecondensate delivered to the 1pype.,|4V substantially below the temperature setting of the fthermostatic valve .4.2. As a result, the precooled.condensate reaching the two-stage :mixer through thepipe r55 causesthe thermostatic .valve 42 .toopen and vthencondenses the steam .released [by the valve. Thus, the make-up water `flowing to `the tank |24 .through the heat exchangerl |.`|.9 takes B. 't, u.s from the condensate .passing through the heat exchanger, and the .coolednndensate.inturn takes B. t. u.s from the .end .of the return line. rlfhe net result is that .B. t. u.fs .are transferred from the return end of ,the system- It is apparent that'both of the described embodiments vof the invention solve theproblem of creating vadequate velocity/in a clear channel steam system that has an exceptionally low ydelnrand `for make-'up watenand ,thatboth embodiments vapply .the same ,principle of ytransferring extraneous liquid that is heated by the system.

Our descriptionin detail of preferred practices of the invention, for the purposes of disclosure and to illustrate the principles involved, will suggest to those skilled in the art various changes and substitutions under our basic concepts. We reserve the right to all such departures from our disclosure that fall within the scope of our 'appended claims.

We claim as our invention:

1. in a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for now-promoting pressure communication through the system, the combination therewith oi means to promote steam flow through said device, said meansincluding: a receiver connected with said return line, said receiver being under substantially less pressure I than the return line,`a valve for releasing nuid from said return' line into said receiver to promote flow in the system, means to cause opening Y action of the valve in response to lowering of the pressure-temperature condition in said receiver and vice versa, a heat exchanger to cool the inyf terior Yof said receiver with make-up water thereby to favor opening `action ofsaid valve for creating flow in the system, and means for preheating at least a portion of said liquid by uid in said return line of the V'system with consequent condensing action in the return line for further nromotion of flowin the system. p

2. In a steam systemfor processing material and additionally supplyingheat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return linev forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means'to promote steam flow through said device, saidumeans including: a receiver connectedwith said return line, said receiver being under substantially less pressure than the return line, avalve for releasing fluid from said return line into `said receiver to promote flow in the system, means to cause opening action oi the valve inresponse'tolowering of the temperature in said receiver and vice versa, a heat eX- ,changerto cool theinterior of said receiver with make-up water thereby toffavor opening action of said valve for creating flow in the system, and

means for preheating at least a portion of said liquid by fluid in` said return line of the system with consequent condensing` action in the return"l line for further promotion of ilow in the system. V3. In a steam .SyStemior processingmaterial Tand additionally supplying heat to a liquidapart from the make-up water demand of the system,

said system having a boiler, at least one steam- ,using device `forprocessing material and a return A line on the low pressure side of the device, said y return line .being closed from the action of .at-

. mospheric pressure so as to create back pressure substantially above4 atmospheric pressure and comparable `to the boilerpressure with corresponding high temperature in the return line, said device and.return ,line forminga continuously7 clear channelfromj said boiler for continuous ilow-promotingE pressure communication through the system, -the combination therewith of means including a heat exchanger'in the return line and a conduit conducting said liquid to the heat exchanger for transferring B. t. u.s from said return line to said liquid, thereby to condense steam in the return line for creating flow through `said channel and steam-using device.

4. `In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means to promote steam ilow through said device, said means including: a valve to release uid fromsaid return line into a region of substantially lower pressure to promote flow in the system, a thermostat for causing opening operation of said valve in response to temperature below a given temperature and closing operation of the valve in response to temperature above said given temperature, said thermostat being positioned to be heated by the fluid discharge of the valve, means to'direct make-up water into mixturwth said discharge of the valve for cooling effect on said thermostat, a heat exchanger in said steam system for heating said liquid, means to convey the cooled condensate from said heat exchanger into mixture with said discharge of the valve for cooling effect on said thermostat, and means to deliver said mixture to said boiler. l l

5. In a steam system for processing material and additionally supplying heat for a' liquid apart from the make-up Water demand o the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for now-promoting pressure communication through the system, the combination therewith of means to promote steam flow through said device, said" means including: a valve to release fluid from said return line into a region of substantially lower pressure to promote flow in the system, a thermostat for causing opening operation of said valve in response to temperature below a given temperature and closing operation of the valve in response' to temperature above said given temperature, said thermostat being positioned to be heated by ,the rluid discharge of i the valve, means to direct make-up water into mixture with said discharge ofthe valve for cooling effect on said thermostat, a heat exchangerY supplied with steam yfrom the system for heating said liquid, a second heat eX- -r changer in the'system supplied" withcondensate and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having aboiler, atleast one steamusing device for processing material and a return line on the low pressure side of'the device, said device and return line forming a clear channel from said boiler, for flow-promoting pressure communication through thesystem, the combination therewith of means to promote steam ow through said device, said means including: a valve to release fluid from said return line into a region of substantially lower pressure to promote flow in the system, a thermostat for causing opening operation of said valve in response to temperature below a given temperature and closing operation of the valve in response to temperature above said given temperature, said thermostat being positioned to be heated by the fluid discharge of the valve, means to direct make-up water into heat-exchange relation with said thermostat for opening action of said valve in response to the demand of the system for water, and means to pass a stream of said liquid in heatexchange relation with the uid in said lreturn line above said valve whereby the liquid is preheated and condensing action occurs above the valve to supplement the velocity-creating effect of the opening action of the valve.

In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for now-promoting pressure communication through the system, the combination therewithof means to promote steam flow through said device, said means including: a valve to release fluid from said return line into a region of substantially lower pressure to promote ow in the system, a thermostat for causing opening operation of said valve in res-ponse to temperature below a given temperature and closing operation of the valve in response to temperature above said given temperature, said thermostat being positioned to be heated by the fluid discharge of the valve, means to direct make-up water into heat-exchange relation with said thermostat for opening action of said valve in response to the demand of the system for water, a heat exchanger included in said return line for preheating at least a portion of said liquid and thereby condensing steam in the return line to supplement the flow-promoting effect of the opening action of said valve, a second heat exchanger supplied With fluid from said system for heating said liquid, meansto return the condensate from said second heat exchanger to supply boiler feedwater for the system, and means to pass at least a portion of said liquid through said rst heat exchanger and then through the second heatexchanger.

8. In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steam-using device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means to promote steam ow through said device, said means including: a receiver connected with said return line, said receiver being under substantially less pressure than the return line, a valve to release uid from said return line into said receiver, a thermostat for causing opening operation of said valve in response to temperature below a given temperature and-closing operation of the valve in response to temperature above said given temperature, said thermostat being positioned to be heated by the fluid discharge of the valve and to respond to temperature changes in said receiver, a heat exchanger in said receiver for cooling the interior of the receiver to favor opening action of said valve, and means to direct a stream of said liquid through said heat exchanger for preheating the liquid and cooling the interior of the receiver.

9. In a steam system, a combination as set forth in claim 8, which includes means to direct make-up Water into heat-exchange relation with said thermostat for opening action of said valve in response to demand of the system for water.

10. In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up lwater demand of the system, said system having a boiler, at least one steamusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for oW-promoting pressure communication through the system, the combination therewith of means to promote steam ow through said device, said means including: a valve to release fluid from said return line into a region of substantially lower pressure for creating velocity in the system, a heat exchanger for cooling the contents of said return line for causing condensation therein to create additional velocity in the system, and means to direct a stream of said liquid through said heat exchanger.

11. In a steam system, a combination as set forth in claim 10, which includes a pump in communication with said return line to convey condensate from said return line to said boiler.

12, In a steam system for processing material and additionaly supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material, and a return line on the low-pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the cornbination therewith of means to promote steam ow through said device, said means including: means to bring said liquid into heat-exchange relation with condensate apart from said return line, thereby to raise the temperature of said liquid and at the same time cool said condensate below the temperature prevailing in said return line, and means to bring said condensate intoA heat-exchange relation with steam that reaches the end of the system through said return line, thereby heating the condensate and at the same time condensing at least a portion of lsaid steam.

13. A steam system as set forth in claim 12, in which said means for bringing condensate into heat-exchange relation with steam intermixes the condensate and steam.

14. In steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steam-using device for processing material, and a return line on the low-pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means to promote steam ow through said device, said means including: means to bring said liquid into heatexchange relation with condensate apart from 113 said return line, thereby to heat said liquid and simultaneously cool said condensate below the temperature prevailing in said return line, means to release steam from said return line, thereby to lower pressure therein for promoting 110W through the system, and means to bring said released steam into heat-exchange relation `with said cooled condensate, thereby to condense the steam and simultaneously reheat the condensate.

15. In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material, and a return line on the low-pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means topromote steam ow through said device, said means including: a rst heat exchanger utilizing steam from the system to heat said liquid, a second heat exchanger utilizing condensate from the rst heat exchanger to preheat said liquid, thereb-y cooling the condensate below the temperature prevailing in said return line, and means to bring the cooled condensate from said second heat exchanger into heat-exchange relation with steam that reaches the end of the system through said return line, thereby to reheat the condensate and at the same time condense at least a part of said steam.

16. In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one steamusing device for processing material, and a return line on the W-pressure side ofthe device, said device and return line forming a clear channel for said boiler for flow-promoting pressure communi-cation through the system, the combination therewith of means to promote steam flow through said device, said means including: a first heat exchanger utilizing steam from the system to heat said liquid, a second heat exchanger utilizing condensate from the rst heat exchanger to preheat said liquid, thereby cooling the condensate below the temperature prevailing in said return line, means to release steam from said return line, thereby to lower the pressure therein for promoting flow through the system, and means to bring the released steam into heat-exchange relation with the cooled condensate from said second heat exchanger, thereby to reheat the condensate and at the same time to condense at least a part of said released steam.

17. In a steam system for processing material and additionally supplying heat for a liquid apart from the make-up water demand of the system, said system having a boiler, at least one stemusing device for processing material and a return line on the low pressure side of the device, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of means including a heat exchanger for transferring B. t. .ufs from said return line to said liquid, therebyl to heat the liquid and transform steam in the return line into condensate, and means to deliver the condensate from the return line direct to the boiler under sustained pressure.

ORVIILE A. HUNT. LOUIN TILLER.

REFERENCES CITED UNITED STATES PATENTS Name Date Schaub Dec. 12, 1933 Number 

